They said their view was cemented by seeing their aunt, Mr Abbott's youngest sister, Christine Forster fall in love with her partner Virginia Edwards.

Frances said being in the design community "where there is quite a large gay population" had illustrated "at the end of the day it is love...love is equal."

"Dad and I have had a few discussions about it," Frances said.

The Abbott Family Christmas Card. Pictured left to right: Margie, Tony, Frances, Louise and Bridget.

"I believe it is inevitable, I believe by the time our generation gets into power I hope and pray something is done about marriage equality and gay rights."

Bridget added: "I just think being gay is a lot more accepted and open for our generation. Chris and Virginia are a completely normal couple. They're exactly the same as Mum and Dad except they happen to both be women."

Australian Marriage Equality national director Rodney Croome said the issue of gay marriage could be a breakthrough election issue this year.

“It certainly was in the US election,” Mr Croome told ABC News 24 this morning.

The lesbian widow taxed $363,000 after her wife's death says she's optimistic the Supreme Court will strike down a statute defining marriage as between a man and a woman. Deborah Gembara reports.

“It will be the same in Australia. If either of our national leaders were to move forward on this issue it would be a big plus for them electorally. It would appeal to younger voters and it would certainly, for Julia Gillard, galvanise the Labor party in support of her.

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